The invention relates to devices suitable for use in optoelectronics, particularly those capable of distributing a propagating mode for a light wave between a plurality of pathways.
Devices of this kind are used particularly in the field of telecommunications where it is frequently necessary to transfer a light wave carrying data from one pathway (wave-guide) to one or more other pathways. The term transfer here refers to switching in which the light wave is integrally switched from one pathway to another, or an operation comprising distributing the light wave between at least two pathways. Optoelectronic components are particularly well adapted to this type of function as there is little space available and moreover the electricity consumption is limited.
Optical devices are already known, generally based on semiconductors, which operate by switching either by adiabatic transformation of modes of the light wave (known by the acronyms DOS or COSTA), or by total internal reflection (known by the English acronym TIR), or again by mode coupling (known by the English acronym EODC).
The invention relates more specifically to devices of the latter type (EODC), more particularly those which have a multilayer structure surmounted by two at least partially parallel primary lines arranged to define, in two regions, straight with the primary lines, two waveguides operating according to a first propagation mode, as well as electro-optical control means placed at a chosen location to vary the coupling between the two waveguides.
A device of this kind is described notably in the publication by M. Schienle, G. Wenger, S. Eichinger, J. Muller, L. Stoll and G. Muller, "One by eight InP/InGaAsP optical matrix switch with low insertion and high cross-talk suppression", IEEE Journal of Lightwave technology, vol 14 No. 5, May 1995. It comprises more precisely a first line segment defining a first wave guide the "exit" end of which is enclosed by the "entry" ends of two other line segments, also defining waveguides and covered with a metallized portion forming the current supply electrode. The three line segments are parallel to one another. To transfer a wave from the first guide to one of the entrances of the other two guides at least one of the two electrodes has to be supplied with current.
Owing to its 1.times.2-type architecture, a device of this kind rapidly becomes a large consumer of current when the number of waveguides becomes substantial. Moreover, this device does not allow the wave to be distributed over two guides until the two electrodes placed at the end of the waveguide through which the lightwave arrives are supplied with current, thereby increasing the current consumption still further. Moreover, the wave initially circulating in the first waveguide cannot remain in it given that the line which defines it is broken off substantially level with the entrances of the two guides which frame it. As a result the device becomes bulky as it requires a "1.times.2"-type architecture for each waveguide through which a given wave arrives. Thus, in order to produce a switch of the 1.times.16 type, 4 levels of waveguide have to be used.